The goal of the proposed research is the physical characterization and elucidation of the mechanism of protoplasmic streaming. The first organisms to be studied will be tha alga Nitella and the fungus Physarum. The principal technique employed will be laser light scattering sepctroscopy, which we have already shown in preliminary experiments to be a novel and effective technique for the observation of protoplasmic streaming. This technique yields instantaneous measurements of the velocity and velocity distribution of streaming, with the particular advantage that motion of submicroscopic particles can readily be observed. Experiments will be performed to determine the effects of temperature, various biochemicals, AC and DC electric fields, and intensity, polarization, and wavelength of incident light on the velocity and velocity distribution of protoplasmic streaming.